package com.example.android.bluetoothlegatt;

public class TI_aes_128 {
    // foreward sbox
public static int sbox[] =   {
//0     1    2      3     4    5     6     7      8    9     A      B    C     D     E     F
        0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76, //0
                0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0, //1
                0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15, //2
                0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75, //3
                0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84, //4
                0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf, //5
                0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8, //6
                0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2, //7
                0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73, //8
                0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb, //9
                0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79, //A
                0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08, //B
                0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a, //C
                0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e, //D
                0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf, //E
                0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16 }; //F

// inverse sbox
public static int rsbox[] =
    { 0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb
            , 0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb
            , 0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e
            , 0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25
            , 0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92
            , 0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84
            , 0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06
            , 0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b
            , 0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73
            , 0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e
            , 0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b
            , 0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4
            , 0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f
            , 0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef
            , 0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61
            , 0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d };

// round constant
public static int Rcon[] = {
        0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36};

    // multiply by 2 in the galois field
    int galois_mul2(int value)
    {
        if ((value>>7) > 0)
        {
            return ((value << 1)^0x1b);
        } else
            return (value << 1);
    }

    // AES encryption and decryption function
// The code was optimized for memory (flash and ram)
// Combining both encryption and decryption resulted in a slower implementation
// but much smaller than the 2 functions separated
// This function only implements AES-128 encryption and decryption (AES-192 and
// AES-256 are not supported by this code)
 public  byte[] aes_enc_dec(int[] state, int[] key, byte dir) {
     int buf1, buf2, buf3, buf4, round, i;

     // In case of decryption
     if (dir == 1) {
         // compute the last key of encryption before starting the decryption
         for (round = 0; round < 10; round++) {
             //key schedule
             key[0] = (sbox[key[13]] ^ key[0] ^ Rcon[round]) & 0xff;
             key[1] = (sbox[key[14]] ^ key[1]) & 0xff;
             key[2] = (sbox[key[15]] ^ key[2]) & 0xff;
             key[3] = (sbox[key[12]] ^ key[3]) & 0xff;
             for (i = 4; i < 16; i++) {
                 key[i] = (key[i] ^ key[i - 4]) & 0xff;
             }
         }

         //first Addroundkey
         for (i = 0; i < 16; i++) {
             state[i] = (state[i] ^ key[i]) & 0xff;
         }
     }

     // main loop
     for (round = 0; round < 10; round++) {
         if (dir == 1) {
             //Inverse key schedule
             for (i = 15; i > 3; --i) {
                 key[i] = (key[i] ^ key[i - 4]) & 0xff;
             }
             key[0] = (sbox[key[13]] ^ key[0] ^ Rcon[9 - round]) & 0xff;
             key[1] = (sbox[key[14]] ^ key[1]) & 0xff;
             key[2] = (sbox[key[15]] ^ key[2]) & 0xff;
             key[3] = (sbox[key[12]] ^ key[3]) & 0xff;
         } else {
             for (i = 0; i < 16; i++) {
                 // with shiftrow i+5 mod 16
                 int tTmpIndex = ((state[i] ^ key[i]) & 0xff);
                 state[i] = sbox[tTmpIndex];
             }
             //shift rows
             buf1 = state[1];
             state[1] = state[5];
             state[5] = state[9];
             state[9] = state[13];
             state[13] = buf1;

             buf1 = state[2];
             buf2 = state[6];
             state[2] = state[10];
             state[6] = state[14];
             state[10] = buf1;
             state[14] = buf2;

             buf1 = state[15];
             state[15] = state[11];
             state[11] = state[7];
             state[7] = state[3];
             state[3] = buf1;
         }
         //mixcol - inv mix
         if ((round > 0 && dir == 1) || (round < 9 && dir == 0)) {
             for (i = 0; i < 4; i++) {
                 buf4 = (i << 2);
                 if (dir == 1) {
                     // precompute for decryption
                     buf1 = galois_mul2(galois_mul2((state[buf4] ^ state[buf4 + 2]) & 0xff) & 0xff);
                     buf2 = galois_mul2(galois_mul2((state[buf4 + 1] ^ state[buf4 + 3]) & 0xff) & 0xff);
                     state[buf4] = (state[buf4] ^ buf1) & 0xff;
                     state[buf4 + 1] = (state[buf4 + 1] ^ buf2) & 0xff;
                     state[buf4 + 2] = (state[buf4 + 2] ^ buf1) & 0xff;
                     state[buf4 + 3] = (state[buf4 + 3] ^ buf2) & 0xff;
                 }
                 // in all cases
                 buf1 = (state[buf4] ^ state[buf4 + 1] ^ state[buf4 + 2] ^ state[buf4 + 3]) & 0xff;
                 buf2 = state[buf4];
                 buf3 = (state[buf4] ^ state[buf4 + 1]) & 0xff;
                 buf3 = (galois_mul2(buf3) & 0xff);
                 state[buf4] = (state[buf4] ^ buf3 ^ buf1) & 0xff;
                 buf3 = (state[buf4 + 1] ^ state[buf4 + 2]) & 0xff;
                 buf3 = galois_mul2(buf3) & 0xff;
                 state[buf4 + 1] = (state[buf4 + 1] ^ buf3 ^ buf1) & 0xff;
                 buf3 = (state[buf4 + 2] ^ state[buf4 + 3]) & 0xff;
                 buf3 = galois_mul2(buf3) & 0xff;
                 state[buf4 + 2] = (state[buf4 + 2] ^ buf3 ^ buf1) & 0xff;
                 buf3 = (state[buf4 + 3] ^ buf2) & 0xff;
                 buf3 = galois_mul2(buf3) & 0xff;
                 state[buf4 + 3] = (state[buf4 + 3] ^ buf3 ^ buf1) & 0xff;
             }
         }

         if (dir == 1) {
             //Inv shift rows
             // Row 1
             buf1 = state[13];
             state[13] = state[9];
             state[9] = state[5];
             state[5] = state[1];
             state[1] = buf1;
             //Row 2
             buf1 = state[10];
             buf2 = state[14];
             state[10] = state[2];
             state[14] = state[6];
             state[2] = buf1;
             state[6] = buf2;
             //Row 3
             buf1 = state[3];
             state[3] = state[7];
             state[7] = state[11];
             state[11] = state[15];
             state[15] = buf1;

             for (i = 0; i < 16; i++) {
                 // with shiftrow i+5 mod 16
                 state[i] = (rsbox[state[i]] ^ key[i]) & 0xff;
             }
         } else {
             //key schedule
             key[0] = (sbox[key[13]] ^ key[0] ^ Rcon[round]) & 0xff;
             key[1] = (sbox[key[14]] ^ key[1]) & 0xff;
             key[2] = (sbox[key[15]] ^ key[2]) & 0xff;
             key[3] = (sbox[key[12]] ^ key[3]) & 0xff;
             for (i = 4; i < 16; i++) {
                 key[i] = (key[i] ^ key[i - 4]) & 0xff;
             }
         }
     }

     byte[] resultByte = new byte[16];
     if (dir == 0) {
         //last Addroundkey
         for (i = 0; i < 16; i++) {
             // with shiftrow i+5 mod 16
             resultByte[i] = (byte)(state[i] ^ key[i]);
         } // enf for
     } // end if (!dir)

     return resultByte;
 }

}
